Seth Woolley's Man Viewer

TIMEGM(3)                  Linux Programmer's Manual                 TIMEGM(3)



NAME
       timegm, timelocal - inverses for gmtime and localtime

SYNOPSIS
       #include <time.h>

       time_t timelocal (struct tm *tm);

       time_t timegm (struct tm *tm);

DESCRIPTION
       The functions timelocal() and timegm() are the inverses to localtime(3)
       and gmtime(3).

NOTES
       These functions are GNU extensions.  The timelocal() function is equiv-
       alent  to the POSIX standard function mktime(3).  There is no reason to
       ever use it.

       For a portable version(1,3,5) of timegm(), set(7,n,1 builtins) the TZ environment variable  to
       UTC, call mktime() and restore the value of TZ.  Something like

              #include <time.h>
              #include <stdlib.h>

              time_t my_timegm (struct tm *tm) {
                  time_t ret;
                  char *tz;

                  tz = getenv("TZ");
                  setenv("TZ", "", 1);
                  tzset();
                  ret = mktime(tm);
                  if(3,n) (tz)
                      setenv("TZ", tz, 1);
                  else
                      unsetenv("TZ");
                  tzset();
                  return ret;
              }

SEE ALSO
       gmtime(3), localtime(3), mktime(3), tzset(3)



GNU                               2001-12-26                         TIMEGM(3)